This invention relates to the passage of objects under sealed conditions between two mutually separated environments, in particular for sterilization or pasteurization plants.
In certain types of such plants a chamber isolated from the external environment is provided in which the objects to be treated are placed. This chamber encloses an environment of hot steam under greater than atmospheric pressure in equilibrium with water at the same pressure and temperature.
An underlying chamber isolated from the external environment can also be provided, filled with colder water at the same pressure. The objects pass through the hotter chamber where they undergo sterilization or pasteurization, then pass through the lower chamber to be cooled and then extracted. In these plants, as in other different applications, there is the technical problem of introducing and extracting the objects into and from said chambers while maintaining the environments within the chambers isolated from the external environment, while taking account of the relatively high throughput of entering and leaving objects.
The known solutions to this technical problem are substantially based on the provision of a type of cylinder with a diameter much greater than its height, and comprising in its cylindrical surface various recesses each able to contain a single object. This cylinder is partially contained within the object treatment chamber and lies partially outside it. By rotating the cylinder a succession of objects are introduced into and extracted from the chamber.
However in these known devices the separation between the two environments is never very efficient, and fluid seepage from one environment to the other is inevitable. Moreover, each recess on entering and leaving carries with it a certain quantity of fluid (air, steam or water, from one environment to the other) and hence produces communication between the two environments. In addition, in known devices the objects are introduced and extracted one at a time in succession, and when the object dimensions change the introduction-extraction cylinder also has to be changed as the recesses must have substantially the same shape as the objects.